单项选择题


Questions 18 to 20 are based on the following passage. At the end of the passage, you will be given 15 seconds to answer the questions.
Now listen w the passage.
Physical and mental tasks were carried out by the women ______.

A.prior to strenuous exercise
B.following strenuous exercise
C.before they were subjected to unusual pressure
D.after they were subjected to unusual pressure